Improving the appearance of the skin has been the goal of many esthetic products and procedures for many years, since a tight skin, without wrinkles or cellulite, has a younger and more appealing appearance. Apart from age related changes, the skin also suffers from exposure to chemical and physical injuries, such as tobacco, cosmetics, esthetics and radiation from the sun and other sources. Those factors contribute to the decrease in collagen production, to reduced elasticity, and the appearance of wrinkles.
A few main approaches to tightening of the skin are common practice today. The surgical approach carries disadvantages related to the anesthesia, the surgical complications, and the healing process, which may cause scars. The chemical peel approach usually involves injury to the outermost layer of the skin—the epidermis—which may cause discoloration. Since collagen fibers are found in the dermis—the subcutaneous layer of the skin, and since heat was shown to contract these fibers and generate their production [Zelickson B D, Kist D, Bernstein E, Brown D B, Ksenzenko S, Burns J, Kilmer S, Mehregan D, Pope K. Histological and ultrastructural evaluation of the effects of a radiofrequency-based nonablative dermal remodeling device: a pilot study. Arch Dermatol. 2004 February; 140(2):204-9], methods of differentially heating the dermis (deep tissue diathermy) have recently arisen.
A unique method of treating the dermis is called Pulsed Electromagnetic Fields (PEMF) therapy. This method usually employs electromagnetic radiation of different frequencies—ranging from static magnetic fields, through extremely low frequencies (ELF) to higher radiofrequencies (RF)—administered in pulses.
PEMF works in more than one way. The radiation absorbed by the tissue can heat the tissue to a desired temperature, depending on the power applied, the frequency transmitted, and, more importantly, the tissue characteristics. For example, the tissue can be heated to denaturation temperatures, which cause tissue damage and coagulation necrosis. Tissue can also be heated to lower temperatures, which can cause the afore-mentioned contraction of collagen fibers.
Another modus operandi involves non-thermal effects, which rely on the reaction of specific tissue components to characteristics of the applied radiation. These effects can be due to large charged molecules and their reaction to various frequencies and their harmonics, charged small ions in the cell membranes affecting cell function and reactions to hormones and chemical signals, charged small ions in the extracellular space and other poorly understood mechanisms.
Furthermore, applying the radiation in pulses was also found to have non-thermal effects. Yet more, specific combinations of frequency, duty cycle and transmitted power can cause specific tissue responses. Recent scientific research has determined PEMF characteristics which can cause desired biophysical responses.
It is now commonly accepted that weak electromagnetic fields (EMF) administered in pulses are capable of initiating various healing processes in fractures, multiple sclerosis and Parkinson's disease, and even delivering pain relief; however it seems that most of the conditions that seem most likely to respond to PEMF are musculoskeletal. Two decades ago, the FDA allowed the use of pulsed radiofrequency electromagnetic fields for treatment of pain and edema in superficial soft tissues. [Rosch, P. J., Markov, M. S., eds. Bioelectromagnetic Medicine, 2004; Marcel Dekker, NY, 251-264].
PEMF can also be used for cosmetic purposes as described above. Several studies have addressed the effect of PEMF on dermal components. For example, in vivo trials showed that pulsed electromagnetic fields of certain field intensities and frequencies increased epidermal collagen synthesis [Ahmadian S, Zarchi S R, Bolouri B. Effects of extremely-low-frequency pulsed electromagnetic fields on collagen synthesis in rat skin. Biotechnol Appl Biochem. 2006 February; 43(Pt 2):71-75]. This newly-formed collagen increases skin elasticity and rejuvenates the appearance of the skin.
In vitro trials showed that PEMF increased the degree of endothelial cell tubulization and proliferation, and augmented angiogenesis primarily by stimulating endothelial release of FGF-2, inducing paracrine and autocrine changes in the surrounding tissue [Tepper, O M et al. Electromagnetic fields increase in vitro and in vivo angiogenesis through endothelial release of FGF-2. FASEB J. 2004 August; 18(11):1231-3. Epub 2004 Jun. 18]. Angiogenesis, the generation of new blood vessels, increases blood flow to the tissue, which in turn increases delivery of oxygen and nutritional substances to the tissue. This effect is most beneficial for injured tissue, promoting rapid and improved healing. The growth factor which is released further enhances the healing process, both in quality and speed of improvement.
The scientific evidence of the effect of PEMF on tissues was utilized in various applications. For example, US20050182462A1 discloses healthy deep tissue heating using PEMF for the purpose of causing contraction and tightening of the skin.
PEMF has also been used to improve skin wound healing. For example, WO08064272 discloses a method of treating a severe diabetic ulcer using PEMF. The patent also discloses the addition of intermittent compression therapy (ICT) and the use of low intensity ultrasound (up to 50 W/cm2), the latter aimed at inhibiting microbial growth.
Other methods of heating the dermis used non pulsating RF radiation, applied by antenna or electrodes. For example, WO98005380 discloses a method of tightening skin using an RF electromagnetic power delivery device.
Improving the results of skin tightening based on dermis diathermy is still a long felt need, both for esthetic and therapeutic purposes.